Optimization of a precise integration method for seismic modeling based on graphic processing unit

General purpose graphic processing unit （GPU） calculation technology is gradually widely used in various fields. Its mode of single instruction, multiple threads is capable of seismic numerical simulation which has a huge quantity of data and calculation steps. In this study, we introduce a GPU-based parallel calculation method of a precise integration method （PIM） for seismic forward modeling. Compared with CPU single-core calculation, GPU parallel calculating perfectly keeps the features of PIM, which has small bandwidth, high accuracy and capability of modeling complex substructures, and GPU calculation brings high computational efficiency, which means that high-performing GPU parallel calculation can make seismic forward modeling closer to real seismic records.

Graphical Processing Unit Based Time-Parallel Numerical Method for Ordinary Differential Equations

On-line transient stability analysis of a power grid is crucial in determining whether the power grid will traverse to a steady state stable operating point after a disturbance. The transient stability analysis involves computing the solutions of the algebraic equations modeling the grid network and the ordinary differential equations modeling the dynamics of the electrical components like synchronous generators, exciters, governors, etc., of the grid in near real-time. In this research, we investigate the use of time-parallel approach in particular the Parareal algorithm implementation on Graphical Processing Unit using Compute Unified Device Architecture to compute solutions of ordinary differential equations. The numerical solution accuracy and computation time of the Parareal algorithm executing on the GPU are demonstrated on the single machine infinite bus test system. Two types of dynamic model of the single synchronous generator namely the classical and detailed models are studied. The numerical solutions of the ordinary differential equations computed by the Parareal algorithm are compared to that computed using the modified Euler’s method demonstrating the accuracy of the Parareal algorithm executing on GPU. Simulations are performed with varying numerical integration time steps, and the suitability of Parareal algorithm in computing near real-time solutions of ordinary different equations is presented. A speedup of 25× and 31× is achieved with the Parareal algorithm for classical and detailed dynamic models of the synchronous generator respectively compared to the sequential modified Euler’s method. The weak scaling efficiency of the Parareal algorithm when required to solve a large number of ordinary differential equations at each time step due to the increase in sequential computations and associated memory transfer latency between the CPU and GPU is discussed.

STUDY ON GIS DATA DIRECTLY INTEGRATED INTO IMAGE PROCESSING

The basic properties to be dealt with ,when considering initially the research needs related to the integration of remote sensing (RS) information into a geographic information system (GIS),are many_sided.The primary combination of remote sensing and GIS is mainly realized by the transforms of data structure .Because of its own limitations,there is an urgent need to investigate the integration of RS and GIS in higher levels.In this paper,we discuss the different types of combinations of RS with GIS,and propose that GIS data should be directly brought into image processing from the beginning.A tentative idea of how to use the method of granularity to study the common processing unit of RS and GIS is described.The example for the determination of granularity of spatial data processing related to run_length_code line is also given.

Research on Network-based Integrated Condition Monitoring Unit for Rotating Machinery

In this paper, a network-based monitoring unit for condition monitoring andfault diagnosis of rotating machinery is designed and implemented. With the technology of DSP(Digital signal processing) , TCP/IP, and simultaneous acquisition, a mechanism of multi-process andinter-process communication, the integrating problem of signal acquisition, the data dynamicmanagement and network-based configuration in the embedded condition monitoring system is solved. Itoffers the input function of monitoring information for network-based condition monitoring and afault diagnosis system.

基于生态系统完整性的自然保护地边界划定方法--以欧美地区的实践为例

科学划定自然保护地的边界关系到保护目标的实现和管理措施的制定,是自然保护地规划和建设的首要环节。该文以欧美地区的实践案例为例,介绍了基于生态系统完整性的自然保护地边界划定方法。首先对现有自然保护地边界划定方法进行梳理,在此基础上介绍了面向实施的景观单元(Operational Landscape Units)的概念和划定流程;其次梳理了韦斯特布鲁克圩田保护边界划定和旧金山湾海岸带保护边界划定的案例;最后为我国自然保护地的边界划定提出建议。

Semantic-based query processing for relational data integration

To solve the query processing correctness problem for semantic-based relational data integration,the semantics of SAPRQL（simple protocol and RDF query language） queries is defined.In the course of query rewriting,all relative tables are found and decomposed into minimal connectable units.Minimal connectable units are joined according to semantic queries to produce the semantically correct query plans.Algorithms for query rewriting and transforming are presented.Computational complexity of the algorithms is discussed.Under the worst case,the query decomposing algorithm can be finished in O（n2） time and the query rewriting algorithm requires O（nm） time.And the performance of the algorithms is verified by experiments,and experimental results show that when the length of query is less than 8,the query processing algorithms can provide satisfactory performance.

基于城市排水过程的内涝高效模拟方法

从实际城市排水过程的角度出发,提出了基于汇水单元概念的城市内涝高效模拟方法.该方法以雨篦子作为出水口来划分汇水单元,进而计算城市地表产汇流、积水深度及分布.同时,引入了当量宽度的概念,实现了明渠与有压流2种状态下管道流量和水位计算方法的统一.基于水量平衡原理,利用雨篦子耦合城市地表与地下管网,并结合孔口耦合管道与河道,构建了地表-管道-河道一体化的求解矩阵.本文将所提出的模拟方法植入成熟的太湖流域模型,并应用常州市城市产汇流与内涝试验基地的监测数据,对该方法的有效性和模型的可靠性进行了评估,以期为城市内涝模拟提供新思路.

基于GPS差分定位的变电站电磁干扰位置识别

由于变电站中各种设备的增加,会导致大量的电磁干扰产生,严重影响变电站的正常运行。为解决这一问题,设计一种基于全球定位系统(Global Positioning System,GPS)差分定位技术的变电站电磁干扰位置识别方法。设计电磁干扰采集平台,实现变电站电磁干扰信号的采集,并进行消噪处理与时域滤波处理。通过GPS差分定位技术实现变电站电磁干扰信号的位置识别。测试结果表明,该方法的单一干扰源平均定位误差低于20 cm,能够实现多干扰源的定位,同时对于较远距离的多干扰源有着较低的定位误差。

曝光单元内线宽均匀度优化对产品工艺窗口的提升分析

阐述随着半导体工艺节点的发展,关键光刻层的最小线宽变得越来越小,由此导致图形边缘位置误差容许范围也越来越小。其中曝光单元内线宽均匀度提升受光罩制作、曝光行为等多方面影响很难控制,导致很多产品在良率验证时出现在Field固定位置发生失效的问题。为此,探讨在28nm HKC+工艺的产品上使用不同的补偿方式优化曝光单元内线宽均匀度,旨在寻找快速高效的补偿方式降低Intra-field CDU,提升图形工艺的工艺窗口。

硫磺回收烟气脱硫消白一体化工艺处理技术

硫磺回收装置焚烧炉烟气经钠法脱硫处理后温度约60℃,直接排放时烟气中水蒸汽过饱和凝结后形成大白烟,造成视觉污染。通过提高烟气温度可以降低烟气湿度,达到消白效果。本技术利用酸性水汽提装置的净化水作为热源,将脱硫塔、烟气-净化水换热器、烟囱三台设备一体化布置,并充分利用各类塔内件的优点,在脱硫塔不同位置设置不同形式的内构件,既达到消白目的,又不增加装置占地面积,系统压降增加值最小,且现场布置美观大方。

A Novel Close-loop Strategy for Integrating Process Operations of Fluidized Catalytic Cracking Unit with Production Planning Optimization

Production planning models generated by common modeling systems do not involve constraints for process operations, and a solution optimized by these models is called a quasi-optimal plan. The quasi-optimal plan cannot be executed in practice some time for no corresponding operating conditions. In order to determine a practi- cally feasible optimal plan and corresponding operating conditions of fluidized catalytic cracking unit （FCCU）, a novel close-loop integrated strategy, including determination of a quasi-optimal plan, search of operating conditions of FCCU and revision of the production planning model, was proposed in this article. In the strategy, a generalized genetic algorithm （GA） coupled with a sequential process simulator of FCCU was applied to search operating conditions implementing the quasi-optimal plan of FCCU and output the optimal individual in the GA search as a final genetic individual. When no corresponding operating conditions were found, the final genetic individual based correction （FGIC） method was presented to revise the production planning model, and then a new quasi-optimal production plan was determined. The above steps were repeated until a practically feasible optimal plan and corresponding operating conditions of FCCU were obtained. The close-loop integrated strategy was validated by two cases, and it was indicated that the strategy was efficient in determining a practically executed optimal plan and corresponding operating conditions of FCCU.

移动式一体化生活污水处理设备的应用进展

随着我国科技的飞速发展,生活污水处理装置也在逐步升级,地下式或半地下式生活污水一体化处理设备应用日益广泛。但是对于处理临时建筑营地、灾后重建营地这一类生活污水,地下式处理设备存在占地面积大、资源易闲置等不足。相比之下,移动式生活污水处理装置具有方便快捷、资源节约、灵活性高等优点,在生活污水应急处理方面具有较好的应用前景。文章总结了近年来移动式一体化生活污水处理设备的处理工艺;介绍了以物理化学法、生物法、组合技术和人工湿地为核心技术的移动式生活污水处理装置的具体构造及其处理效果;从资源利用和长期规划的角度对移动式和地下式生活污水处理装置进行比较,突出移动式生活污水处理装置的灵活性、经济实用性;通过分析农村生活污水处理情况,对未来农村生活污水处理模式进行探讨,提出小型污水处理厂与移动式生活污水处理装置并存的运行方式;对移动式生活污水处理装置的发展趋势进行了展望,重点强调了高级催化氧化和膜分离工艺对其发展的推进作用,具有重要理论与现实指导意义。

保测合智纵向集成的智能变电站过程网故障诊断与定位方法

在城市变电站小型化的要求下,保测合智纵向集成的智能变电站成为新趋势,而过程网是智能变电站实时信息的交互中心,准确快速地诊断与定位过程网故障能及时排除二次系统隐患,保障变电站的安全可靠运行。为此,以某110kV智能变电站为对象,针对保测合智纵向集成的智能变电站过程网的故障诊断与定位方法开展研究,根据信源/信宿矩阵、端口物理/逻辑联接矩阵,构建保测合智纵向集成的智能变电站IED的端口报文信息传输链条模型;并基于此,针对不同类型的过程网络故障类型分析了基于SV或GOOSE报文异常告警信息的过程网络故障特征,从而形成过程网络的异常故障类型辨识与故障定位判据,最终提出了一种保测合智纵向集成的智能变电站过程网的故障诊断与定位方法,为保测合智纵向集成的智能变电站过程网实时信息传输链条模型的构建提供了方法。

应用Python-GPU求解的实时混合试验方法研究

提出了基于Python和图形处理器(GPU)数值求解的实时混合试验系统。将土-结相互作用系统作为试验模型,使用Python-GPU代替CPU数值求解,对提出的实时混合试验系统进行了仿真与试验验证。研究结果表明,使用Python-GPU对无条件稳定算法求解,积分步长20 ms时GPU实时求解模型自由度超过24000,是同一台计算机CPU求解规模的7倍左右,提升了实时混合试验的试验能力。

工业数据驱动的加氢裂化装置多工况切换过渡状态检测

加氢裂化装置运行工况众多且切换频繁,而不同稳定的工况间切换必然存在过渡状态,可能会引起装置运行状态波动,甚至引发事故。通常,操作员会基于专家经验判断装置当前处于稳定或过渡状态,分别采取相应的监控和调整策略。然而,人工判断具有个体差异、经验积累周期长等不足,可能导致过渡状态判断不够准确,故提出一种加氢裂化装置多工况切换过渡状态检测方法,首先,结合工业大数据和装置过程机理,针对工业采集数据运用了小波降噪和平滑,再利用相关分析法和主元分析(principal component analysis,PCA)进行数据降维,剥离了相关性强的变量所带来的额外计算成本和信息干扰,将滑动窗拆分并计算移动方差,再与Kmeans(K均值)聚类相结合,实现了加氢裂化装置的过渡态检测。最后,与经典K-means聚类和层次聚类方法进行对比验证,证明了所提方法具有更好检测能力。

分离型轮机模拟器通用分布式处理单元的设计

由于分离型轮机模拟器上位机集成了实船上各种轮机设备的仿真模型,针对不同的设备采用了不同的下位机板卡,使得应用层通信协议存在差异,不仅造成下位机设备重复开发,而且增加了上位机仿真模型的开发难度。针对此情况,基于STM32F7微处理器设计含有数模数据输出与输入及网络通信的硬件电路,并在集成开发环境Keil5中,构建包含通信、数据、任务三层结构的软件程序,实现了设计初衷。经实验验证,所设计单元具有较高的可靠性和实时性,并实现上位机与下位机的信息同步,使分离型轮机模拟器对具有协议统一、通用性强的通信板卡的需求得到满足。

基于RAPIDS的无参DBSCAN算法

具有噪声的基于密度的空间聚类(Density‑based spatial clustering of applications with noise,DBSCAN)能够发现不同密度和大小的类簇,对噪声也有很好的鲁棒性,被广泛地应用到数据挖掘的任务中。DBSCAN通常需要调整参数MinPts和Eps以达到更优的聚类效果,但往往在搜索最优参数的过程中会影响DBSCAN的性能。本文从两个方面优化DBSCAN,一方面,提出一种无参的方法优化DBSCAN全局参数选择。无参方法利用自然最近邻获得数据集的自然特征值,并将自然特征值作为参数MinPts值。然后,根据自然特征值计算自然特征集合,利用自然特征集合中的数据分布特性,分别采取统计最小值、平均值和最大值3种方式得到Eps值。另一方面,采用集成数据科学实时加速平台(Real‑time acceleration platform for integrated data science,RAPIDS)的图形处理器(Graphics processing unit,GPU)计算加快DBSCAN算法的收敛速度。实验结果表明,本文提出的方法在优化DBSCAN参数选择的同时,取得了与密度峰值聚类(Density peaks clustering,DPC)相当的聚类结果。

动车组车载非实时数据下载及应用平台设计与实现

为满足铁路动车组故障原因深入分析、趋势规律预测等需求,分析车载非实时数据现状,提出采用无线局域网(WLAN,Wireless Local Area Network)结合5G移动通信公网进行非实时数据下载的方式,设计了动车组车载非实时数据下载及应用平台。通过海量数据处理监控、批量高效数据解析及数据完整性校验等关键技术,实现车载非实时数据的采集传输、数据监控、数据解析、数据共享及综合展示等功能。该平台的实现可进一步推动铁路动车组非实时数据的下载建设,对于动车组故障分析及运用状态评估预测等研究具有重要意义。

燃料型重整装置改造新增二甲苯产品分离方案研究

针对已运行的燃料型重整装置进行增产混合二甲苯改造,提出了几种改造方案并对其进行了流程模拟和比较研究。着重对比了“两塔热联合流程”“分壁塔流程”“分壁塔+两塔热联合流程”3个方案的重沸器热负荷、蒸汽及燃料消耗,对比发现3个方案的综合能耗分别较基础方案低53.1%、22.7%、71.2%。集成了两塔热联合技术、分壁塔技术二者优点的“分壁塔+两塔热联合流程”方案节能效果最佳。分析了分壁塔工业应用的两个案例,其重沸器负荷均较常规两塔重沸器负荷之和降低30%以上,体现了分壁塔的节能效果。二甲苯塔加压操作,塔顶物料用作脱C7塔重沸器热源的两塔热联合流程相较于分壁塔节能25%,类似工况不建议采用分壁塔。研究结论可为同类装置实施“减油增化”改造提供借鉴。

Deep Learning Applied to Computational Mechanics:A Comprehensive Review,State of the Art,and the Classics

Three recent breakthroughs due to AI in arts and science serve as motivation:An award winning digital image,protein folding,fast matrix multiplication.Many recent developments in artificial neural networks,particularly deep learning(DL),applied and relevant to computational mechanics(solid,fluids,finite-element technology)are reviewed in detail.Both hybrid and pure machine learning(ML)methods are discussed.Hybrid methods combine traditional PDE discretizations with ML methods either(1)to help model complex nonlinear constitutive relations,(2)to nonlinearly reduce the model order for efficient simulation(turbulence),or(3)to accelerate the simulation by predicting certain components in the traditional integration methods.Here,methods(1)and(2)relied on Long-Short-Term Memory(LSTM)architecture,with method(3)relying on convolutional neural networks.Pure ML methods to solve(nonlinear)PDEs are represented by Physics-Informed Neural network(PINN)methods,which could be combined with attention mechanism to address discontinuous solutions.Both LSTM and attention architectures,together with modern and generalized classic optimizers to include stochasticity for DL networks,are extensively reviewed.Kernel machines,including Gaussian processes,are provided to sufficient depth for more advanced works such as shallow networks with infinite width.Not only addressing experts,readers are assumed familiar with computational mechanics,but not with DL,whose concepts and applications are built up from the basics,aiming at bringing first-time learners quickly to the forefront of research.History and limitations of AI are recounted and discussed,with particular attention at pointing out misstatements or misconceptions of the classics,even in well-known references.Positioning and pointing control of a large-deformable beam is given as an example.